The present invention concerns a semiconductor device and fabrication method thereof and, more in particular, it relates to a semiconductor device having a low-resistivity wiring structure and a fabrication method thereof.
When wirings are formed on a hill and valley structure in existent semiconductor devices, an insulator has at first been deposited on the hill and valley structure to planarize the surface and wiring have been formed on the insulator as described in Japanese Patent Laying Open Hei 1-140644.
If wirings are formed directly on the hill and valley structure, it sometimes result in a portion lacking in a predetermined thickness and, in an extreme case, leads to disconnection, but wirings formed by the method described above can satisfy the required thickness and causes no disconnection.